Flashcards in Toxocology Deck (24):
Study of adverse effects of xenobiotic compounds
- chemical properties
- biological effects,
Any substance capable of causing a DELETERIOUS RESPONSE in a
Poisons that originate FROM LIVING ORGANISMS
(i.e., zootoxins from
animals, phytotoxins from plants, bacterial toxins)
Toxic substances, chemicals produced by HUMAN-MADE activities
Factors Determining Toxicity
2. Duration/Frequency of Exposure
3. Route of Exposure
4. Toxicokinetics (ADME)
5. Physiological Factors
AMOUNT of drug, toxin or toxicant that REACHES THE SITE OF ACTION in an animal
LD50 vs LC50
Essential nutrients or non-nutritional toxic substances imparting beneficial effects, but ADVERSE EFFECTS AT HIGH OR LOW DOSES
– Exposure to a chemical for < 24 hrs
– SINGLE DOSE occurring from a single incident
• Iron overdoses in pigs
• Insecticide ingestion in animals
– Exposure to a chemical for < 1 month
– Repeated doses
• Dogs eating aflatoxin contaminated food for 4 weeks
Exposure to a chemical for 1 - 3 months
Exposure to a chemical for > 3 months to years
Why are birds more sensitive to gases?
– Highly efficient at exchanging gases for high oxygen delivery to muscles for flight
– High metabolic rates, small size
– The air breathed is rapidly distributed to tissue
1 - IV
Which parenteral routes pass thru the liver before going to the body?
• used to experimentally mimic oral exposure
What does ADME stand for?
A - absorption
D - distribution
M - metabolism
E - excretion
What factors is most important regarding absorption of a toxin/toxicant?
- Depends on the degree of ionization @ specific pH value = pKa of drug
Non-ionized drugs are ____ soluble?
Barium sulfate = contrast radiography
• 5.4 - 6.8
• 5.4 - 6.8
• 2 - 4
Hay containing > 1% nitrate in rumen ---> ...?
Normally the Ruminal flora converts Nitrate --> nitrite --> ammonia to protein
• ↑ Nitrate conversion excess microflora capacity
--> Nitites absorbed in blood
--> oxidized Hb
--> Methemoglobin cannot release O2 to tissues
--> cyanosis + metHb-emia!!
How does GI motility affect drugs ADME?
↓ gastric motility / emptying
--> ↑ absorption